Cyclades PC400 - Manual (Page 40)

Cyclades-PC400
40
Appendix A - Linux
Installation Manual
• status (active or inactive) - if this item is not active, the script will not be executed.
• user - the process will be run with the privileges of this user, who must be a valid local user.
• source - pathname of the crontab file.
When the /etc/crontab_files file contains the following line:
active root /etc/tst_cron.src
and the /etc/tst_cron.src file contains the following line:
0-59 * * * * /etc/test_cron.sh
crond will execute the script listed in tst_cron.sh with root privileges each minute.
Another option is to use the crontab command to interactively modify the crontab file. Its syntax is:
crontab [-u user] file or crontab [-u user] { -e | -l | -r }
where
-e = edit user’s crontab
-l = list user’s crontab
-r = delete user’s crontab
Type man cron and man crontab at the Linux prompt for more information.
The DHCP (Dynamic Host Configuration Protocol) Client
DHCP is a protocol that allows network administrators to assign IP addresses automatically to network devices.
Without DHCP (or a similar protocol like BOOTP), each device would have to configured manually. DHCP
automatically sends a new IP address to a connected device when it is moved to another location on the
network. DHCP uses the concept of a fixed time period during which the assigned IP address is valid for the
device it was assigned for. This “lease” time can vary for each device. A short lease time can be used when
there are more devices than available IP numbers. For more information on how to set your server up as a
DHCP client or server, see RFC 2131 or the DHCP pages at www.linuxdoc.org